wizby

I just pick up a set of the hudy balance tools and put my new EC on them. The car is complete and it balances perfectly, without any additional weights added. No light weight servo's and the transponder is on the servo side. I expected needing left side lead. Nova engine & medium conical, 2630 pipe. What gives? After reading some past posts I didn't expect this.

Cobra zz

Seems that regular servos and lack of receiver box equalizes side weight...

wizby

Guess I have an extra set of XRAY balance weights.

DS Motorsport

iTrader: (2)

Did you made sure the surface where the balance pins were placed on is completely leveled?.
And how did you measured the car's balance, just by eyeballing it?.
You can measure the balance by leveling the surface with a spirit level and a small spirit level on the cars radioplate. If both the spirit levels are centered then your car is balanced.
Another way is leveling the surface and use the downstop measuring blocks to measure the distance between the block and the wheels. If you do this with setup wheels and measure both sides and the distances are equal you can consider the car balanced as well.

I'm questioning the way you measured it because I think the car can't be balanced with the equipment you are using. When I was using one low profile servo, no receiver box and had the transponder on the servo side, I needed the Lipo balancer plus 15gr to balance the car.
The only thing I could think of is that the 2630 pipe is heavier as most pipes. I mainly use the 2602 and 2604. Will weigh the 2652 when it is delivered.

wizby

The Hudy set up board is level. Bubble level says so. The downstops are set equally,tires are same diameter and the distance between the board and front tires is the same. I think placeing a level on the radio plate will unbalance the car. I did not expect this result.

Cobra zz

Do you guys know these RCMarket Ti pivot balls ? Is it well worth ?

http://rcmarket.com.hk/product_info....oducts_id=2423

musti72

I found a new trick to balance the car:

http://www.racing-cars.com/images/S1...CING_JIG_w.pdf

I have just tried it 10mins ago with a pair of scales and hudy balance pin, and it reads very accurate. To my understanding, you should setup the car exactly symetrical first(shock adjusting nuts clearance same l/r) and then put the car on this system. Add weigh until you read same values, and you have a perfectly balanced and tweaked car.
Did I miss something?

rmdhawaii

iTrader: (4)

Do you have a set of setup wheels lying around? I wonder if the results would be the same or different....

musti72

Yes, I also tried it with a pair of setup wheels, and the difference between left-right was the same, but since setup wheels were heavier than foam tyres, total weight was different.

I tried to add some weight on the car, so far so good. I got the results I expected, and you can read it on the scales how much of the weight loaded on each wheel. For example when I add 10grams to the left of the car, left wheel reading increases 7grams, and the other 3 grams, and it depends where you add it of course.

DS Motorsport

iTrader: (2)

I've seen this method as well and I believe it has it plusses and minuses.

The minuses are that I think it is really hard to get some accurate and repeatable results. By measuring the balance like this there are quite a few variables who can mess up your readings. For instance unequal springs, the scales need to be leveled, minor binding in suspension. You have to realize we are talking about grams, so the slightest thing could mess it up.

The plus about this way of measuring is you will balance it like it is used: the contact patch of the wheels.

But before balancing it like this I would start with putting the car on both Hudy pins. And maybe try finetuning it with the method mentioned above.

rx7ttlm

iTrader: (30)

the problem with the hudy pin, and balance scale combo is two fold. Your assuming the spring free length and a lot of other things are exactly the same. and the friction from the pin and chassis will only get you close. A better suggestion. Is to get 4 scales. make sure your ride height is set, on a level platform. Then you check your chassis for level once its all ready to run with 1/2 tank of fuel. Place the car on your 4 scales. take the sum of the left side car weight, and the sum of the right side car weight. These should be the same +/- 5 grams. Then you take the sum of the diagonals, LF + RR, and compare that to the sum of the RF and LR. These last numbers are your cross weight. This is actually what your making equal when your setting "tweak" on an rc car with other methods like tweak board or exacto knife. Assuming your suspension isn't binding, and every thing is set properly. Your car will never handle better. This is the same way we set up cars in 1:1 motorsports. Also prior to this you must make sure track width is equal front and rear track width (measure from the hub or wheel, to the centerline of the chassis to make sure that your not running an offset without knowing.

musti72

Yes, I have 4 scales and tried what you said, but with a tiny amount of change in one spring preload, all four corner values change. So with unequal springs it will be off as well. They even change when I lift up the car and put it again on the scales, and Im sure there wasnt any binding or dampening problems.

To sum up, I found it really hard to use, but once you manage to do it correctly, I think it will be best way too.

rx7ttlm

iTrader: (30)

Well its the most accurate way to use. There is actually a really easy way to understand how it all works. If you add spring preload to the lf, you will increase the corner weight of the lf and the rr. But simply. If your left side weight isn't the same as the right side weight. (do the math) then you need to move ballast to get the correct values. and since its how the car will hit the track (assuming you made sure the tire diameters left and right are the same. you will have better on track performance.

musti72

So I have tested setting it up again today on 4 scales, and found some interesting results.

I found out that it doesnt read consistent because of excessive play and slop on suspension arms, hubs, pivot balls, axles, etc... Well, its a 2 year old car with lots of hard racing. When I roll the car, everything changes. I hope that with a new and well maintained car, this shouldnt be as much as it is now.

Second thing that I found out that it reads the fr+rr or fl+rl same ALL THE TIME. So you're right its a better if not the best way to balance the weight of the car.

Here are some examples: (no different adjustments made, just by different compressing of the suspension)

FL: 373 FR: 327
RL: 411 RR: 424

FL: 372 FR: 330
RL: 412 RR: 420

FL: 364 FR: 334
RL: 420 RR: 416

So I have a question: How can we know that we put the car on scales exactly same compressed all the time? I mean the settling thing of the shocks, its uncontrollable.

rx7ttlm

iTrader: (30)

ok, so that's a little more spread than I usually get. Assuming you have minimal friction / binding your values shouldn't shift quite that much. I would go through and find out whats going on. Hint, I use the serpent pivot ball adjusters (white nylon one piece) they seem to work more consistently as far as pre-load and not binding run to run. check your hinge pins (metal rods that connect arms to bulkheads) for straightness as that can bind things up, check all your camber/ toe links to make sure they are all free and not binding. When I build a corner I take my time and examine EVERY pivot ball and socket for fit. Minimal slop, but not binding at all is key, it should be smooth like a strippers ass. No bumps, sags or binding. Cause that's just gross and also last but not least rear swaybar links and SWAYBAR. A lot of people overlook binding in the swaybars them selves. I polish my front bar ball and receiver. rear bar (wire type), should be adjusted with the links disconnected. preload the grub screws (turn in) till it stops moving freely, and one at a time take the preload out till it falls under its own weight. repeat for other side. I haven't checked numbers in a while. but I will post my own corner weight variance later. also make sure the shocks have EQUAL rebound values and are fresh. if the shock seals have swelled or anything is out of sorts that can affect things too. Hope this helps.